Field of the Invention
The present invention relates to the management of preventative maintenance by diagnosing possible motor starter or industrial control panel problems through the monitoring the temperature behavior of motor starters in a group.
Discussion of the Art
A motor starter, also known as just a “starter,” is the control device dedicated to an electric motor and typically comprising an overload relay and a contactor, as is known in the art. A group of closely associated starters; located in proximity in the same environment is sometimes referred to as a “starter island.” It is often the case that a plurality of motors are grouped together in functional units to control several tasks within a function and there will be a plurality of starters grouped together in a common location such as in a cabinet remote from the motors. Examples may include a conveyor line with multiple sections, manufacture of an item with multiple operations requiring different motors, etc. More broadly, the starters in a starter island are often located in control panels. As known to those in the art, industrial control panels are an assembly of two or more power circuit components, control circuit components, or any combination of power and control circuit components. Industrial control panels are typically enclosed assemblies of industrial control equipment, such as motor controllers, switches, relays and auxiliary devices. The panels may include disconnect means and motor branch-circuit protective devices. Control panels are intended for general-use industrial applications for the control of heaters, lighting, motors, pump loads, industrial machinery, cranes, refrigeration equipment and fountains or a combination of these loads.
Because overheating of starters and motors represents a large expense in lost energy, replacement costs, and downtime, etc. to the operator, preventive maintenance for the starters and motors is a practical necessity. More and more today, it is desired to use less space to accommodate electrical distribution and control equipment. Increasing density in the physical placement of the starters may increase the incidence of heat problems.
In the known art, heat protection for starters is accomplished by a simple “limit and trip” approach whereby a temperature limit is set and the motor is shut down if it exceeds the temperature, i.e. the typical temperature protection is a simple threshold-cross function, executed by devices in isolation. However, this manner of protection is ad hoc and does not present much functionality for preventative maintenance purposes.